Process for sintering fine ores, flue-dust, purple ore, and the like.



Ores Flue-Dusti UNITED STATES PATENT oE 1oE CARL GIESECKE, OF BAD KARZIBURG, GERMANY.

PROCESS FOR SINTERTNG FINE OBES, FLUE-DUST, PURPLE ORE, AND THE LIKE.

Specification of Letters Patent.

Patented Nov. 21, 1916.

Application filed August 30, 1916. Serial No. 117,735.

To all whom it may concern:

Be it known that I, CARL GmsEcKE, engineer, subiect of the King of Prussia, Emperor of ermany, residing at Bad Harzburg, in the Duchy of Brunswick, Germany, have invented certain new and useful I mprovements in Processes for Sintering Fine Purple Ore, and the like, of which the fol owing is a specification.

My invention relates to a process for sintering agglomerates of fine ores, fluedust, purple ore and the like by subjecting such agglomerates to sintering treatment in a shaft furnace, i. e. a vertical kiln of the type used in European cement-industry and similar to the cupola furnace.

The purpose of my invention is to ob tain by means of the inexpensive shaft furnace a sintered product which may be charged with special advantage on account of its strength, porosity and suitable size into the blast furnace.

The process consists in distributing, in such a way, relatively to the agglomerate, the fuel (coke or coal) which is introduced into the shaft furnacetogether with the agglomerate, as to avoid the deleterious effects, upon the sintered product, of concentration of the ash produced during the process.

In sintering bricks or otherwise formed agglomerates of fine ore, flue dust, purple ore and the like, for further treatment in the blast furnace it has been found that the ash of the coke or other suitable coal, especially non-bituminous coal (anthracite) serving as fuel has a disadvantageous effect on the products, when working accordi to the rules of practice for other meta lurgical shaft furnaces.

To obtain quick working of the smter furnace it is, important, that the charge is located in such a manner that gas may penetrate as easily as possible. This is obtained in known manner by using lump coke, The consequence of uc lumps is a very im allar distribution of the ash residuesand 'e concentration of same at some places, as

the charge like nests.

often only 810% of coke are required. The ash residues however easily form liquid silicates of ferrous oxid or ferric oxid with the adjacent parts of the charge rich in iron and such reaction takes place where a lump of coke existed, thus being distributed within Owing to the high amountof silicic acid to be found in nearly all kinds of coke, the'said effect is very troublesome, for not only are larger blocks of the sintered products" formed of the agglomerates at the easily melting places but the sintered product in the neighborhood of such places will also be made unsuitable for further reduction by means of carbonic oxid in the blast furnace by the vitrification taking place in a high degree.

The new process consists in using coke or coal in lumps as small as possible between the bricks or otherwise agglomerated fine ores and the like. Hereby 1s obtained the favorable effect that the silicic acid of the fuel facilitates the sintering (after the car bon has been burned) by the reaction with the agglomerates on a considerably enlarged surface; for the same reason no accumulations of liquid slags are formed and thereby the disadvantages formerly explained being avoided. The equal distribution of the fine fuel in the charge has moreover another important advantage for the roduct and the good working of the sinter urnace. The pieces (bricks and the like) fed to the shaft furnace have only a relatively low solidity. If these pieces are. resting upon a sharp edged lump of coke of that size as used for instance in cupola furnaces they are broken into fragments of small size and then obstruct the draft. But .by charging coke breeze as fuel the interstices between the ore bricks are filled out to some extent, the

breeze acting like a cushion, so that the' that by means of high temperature, 5. e. quick action upon the charge, and quick cooling a sintered crust is produced which surrounds the core of a mass not sufliciently sintered. In this case the good distribution of the ash facilitates the formation of an easily sintering "crust without one brick uniting with another one to form a homogeneous mass which effect would occur only in case the ash accumulates to a greater extent at some places.

The process may be improved by mixing and then agglomerating a part of the small sized fuel with the fine ore and the like and adding the rest as coke or coal of small lumps between the bricks. Hereby the concentrated accumulation of the ash is still more effectively prevented. The ash of the fine fuel contained in the agglomerate owing to its great distribution has the further advantage that it provides an easily sintering skeleton in the iron ore and effects adhesion without the iron ore itself as a whole being heated too highly.

The fuel to be distributed over the agglomerate is preferably used in a special form 15. e. the so-called coal washings or colliery-slimes which are obtained as a byproduct in coal washing plants or in the treatment of coal at other places. These coal washings or colliery slimes often contain considerable amounts of ash which when mixing the fine ore and the like with the slimes are also distributed in the manner of skeletons in the ore. During sintering this skeleton of very fine ash particles forms in the agglomerate a relatively easily sintering substance with the ore. The quality of the agglomerate is still more improve by adding colliery-slimes containing a high percentage of clay with a good binding actlon. In this case the addition of such slimes exerts a cementing action upon the agglomerates which therefore enter the sintering furnace wherein they are destroyed to a less extent. This last named effect'may also be obtained by thoroughly mixing fine coal with fine clay or fine iron ores rich in clay and thereby producing artificial slimes.

It is not necessary that at the beginning the material to be worked shall be in a fine state, on the contrary it is sometimes preferable to crush it into small pieces before agglomerating the same. Thls is for instance carried out if some pieces are too small for directl charging the blast furnace and too large or obtaining a durable agglomerate in the shaft furnace. If such an ore 1s crushed a brick or the like agglomerate may be obtained therefrom in a suitable press which easily sinters in the shaft furnace especiall if colliery-slimes rich in clay have been ad ed.

Sometimes the substance to be agglomerated is not entirely present as oxid as is the case with ore but consists to a greater or smaller percentage of metallic iron (chips, filings, shavlngs and the like) the surfaces of which often show rust. Such metallic substances also may be treated with good results by the improved process. Preferably they are mixed with slimes containing clay and coal and then treated by strong presses to obtain bricks or otherwise shaped bodies which after sintering in the shaft furnace by means of inter osed fine coke give a prodnot which may used in blast furnaces, cupola furnaces, open hearth furnaces, crucibles, or electric furnaces for the production of iron or steel.

The substances sintered according to this process leave the shaft furnace as a mass in which the agglomerates stick together very loosely and therefore form a good charge for the blast furnace. For the same reason the shaft furnace may be worked continuously as the sinterin products may be removed in a very simp e manner by means of automatically acting removal devices.

What I claim is:

1. The herein-described rocess of sintering finely-divided materia containing iron, which consists in mixing such material with slimes; agglomerating the mixture; and heating the agglomerate; together with finelydivided fuel, in a shaft furnace.

2. The herein-described rocess of sintering finely-divided material containing iron, which consists in mixing such material with slimes containing a high percentage of clay; agglomerating the mixture; and heating the agglomerate, to ther with finely-divided fuel, in a shaft rnace.

3. The herein-described process of sintering finely-divided material containing iron,

which consists in mixing and ag lomerating such material with finely-divide fuel; subjecting the agglomerates to pressure to form them into more or less regular bodies; distributing fuel in the form of small lumps over said bodies and between their interstices, in a sintering furnace; and subjecting said bodies to rapid heating and cooling in said furnace.

4. The herein-described process of sintering finely-divided material containing iron, which consists in mixing and agglomerating such material with slimes; subjecting the agglomerates to ressure to form them into more or less regu ar bodies; distributing fuel in the form of small lumps over the said bodies and between their interstices, in a sintering furnace; and subjecting said bodies to ra id heating and cooling in said furnace.

5. he herein-described process of sintering finely-divided material containing iron, which consists in mixin and agglomerating such material with s es containing a high percentage of clay; subjectin the agglomerates to pressure to form t em into more or less regular bodies; distributing fuel in the form of small lumps over said bodies and between their interst1ces,'in a sinterin furnace; and subjecting said bodies to rapi heating and cooling in said furnace.

In testimony whereof I have hereunto set my hand in presence of two subscribing witnesses.

CARL GIESECKE. Witnesses:

WILHELM LEHRKE, WILHELM KAMMERHOFF. 

